As described in the literature, p-benzobisoxazole polymers, e.g., poly{[benzo(1,2-d:5,4-d')bisoxazole-2,6-diyl]-1,4-phenylene}, can be synthesized with inherent viscosities of up to 3.7 dl/g. These polymers possess high thermooxidative stability and, because of their all-para, rod-like character, they are capable of forming liquid crystalline phases in concentrated solutions of methanesulfonic acid. Ultra-high strength, high modulus fibers possessing a high degree of oriented, crystalline character can be obtained from these solutions. However, attempts to cast strong films from the methanesulfonic acid solutions have been unsuccessful. It has been possible to obtain only very brittle films.
It is a principal object of this invention, therefore, to provide para-oriented polymers which can be used to fabricate films and composites having outstanding physical properties.
Another object of the invention is to provide para-ordered aromatic heterocyclic polymers containing diphenoxybenzene structures.
A further object of the invention is to provide a process for preparing the polymers.
Still another object of the invention is to provide films prepared from the polymers.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.